<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#one{width:100px; height:100px; background:red; position:absolute;top:50px;left:0;/*left:600px*/}
</style>
<script>
//逐渐变慢    越接近终点，速度越小。    距离越小，速度越小。距离越大，速度越大。
	//处理小数
var timer=null;
function startMove(target){
	var one=document.getElementById('one');
	clearInterval(timer);
	timer=setInterval(function(){
		var speed=(target-one.offsetLeft)/8;
		speed=speed>0?Math.ceil(speed):Math.floor(speed);
//		if(speed>0){
//			var speed=Math.ceil(speed);	
//		}else{
//			var speed=Math.floor(speed);
//		}
		if(one.offsetLeft==target){
			clearInterval(timer)	
		}else{
			one.style.left=one.offsetLeft+speed+'px';	
			document.title=one.offsetLeft+','+speed;
		};	
		
	},30);	
};


</script>
</head>

<body>
<input type="button" value="运动" onclick="startMove(300)" />
<div id="one"></div>
<span style=" position:absolute;left:300px; height:500px;width:1px; background:#000;"></span>
</body>
</html>

